Grey whippet dog in a jumper
© Unsplash

Everything you need to know about heart murmurs in dogs

By Daniel Mar Journalist

Updated on the

Heart murmurs in dogs is a serious disease. The degree and intensity of the murmurs will indicate how aggressive needs to be the treatment

A heart murmur is a disease which commonly affects dogs. Unfortunately, it is hard to identify by pet parents with no medical training.

A heart murmur is a sound made by an abnormal blood flow inside the heart. Therefore, this disease is mostly a malfunction of the heart valves. As a result, the heart makes heart murmurs in dogs.

Learning the basics about heart murmurs in dogs

This disease can result in birth which means that it is congenital. Most cases of heart murmurs in puppies are a direct result of genetic inheritance. Be careful though, puppies can experience what is called “innocent” murmurs (which are temporary) due to body grow. Nevertheless, dogs can also get this disease due to a heart disease or simply the ageing process. That is why all murmurs in adult dogs indicate a heart disease.

Normally, a healthy heart has two audible sounds, the famous “lub” and “dub”. These sound uniform. Likewise, they have a constant loudness which means that none is louder than the other. “The "lub-dub" sound is made by the heart valves closing as blood exits the heart chamber”, said Dr Karen Shaw Becker. If one (or both) of these valves don’t close appropriately, the pressure will make some blood flow back into the heart. This is when you hear the murmur.

Since this disease is very common, veterinarians have carried out hundreds of studies. Fortunately, there is a grading scale that measures the loudness of the heart murmurs in dogs. Depending on the intensity, you can determine the severity of the disease:

  • low sound, hard to detect.
  • soft murmur heard clearly by a vet.
  • reasonably loud murmur which is easy to detect.
  • moderately loud murmur with no vibration.
  • loud murmur with vibration.
  • very loud murmur with vibration. Heard without a stethoscope.

Causes of heart murmurs in dogs

There are several heart diseases that cause heart murmurs in dogs. As a result, you can tell how long can a dog live with a heart murmur. Generally, there are five causes of heart murmurs:

  1. Narrow arteries.
  2. Valves malfunction.
  3. Inflammation of the heart.
  4. Abnormalities in the heart.
  5. Heart valves lesions.

Murmurs can occur on the right side of the heart due to tricuspid regurgitation. It causes the heart’s tricuspid valve to stay fairly open thus allowing backflow of blood. On the left side, mitral valve prolapse or stenosis of aortic valves cause heart murmurs. Heart murmur in puppies is often a direct result of congenital lesions. However, murmurs in adult dogs are a consequence of acquired lesions in the heart valves.

What are the symptoms of heart murmurs in dogs?

Heart murmurs can present themselves as different sounds. They change according to which stroke of the heart they are linked to. However, this can be quite technical if you are not a veterinarian. Therefore, if you want to know the symptoms of a heart murmur in dogs, just watch out for:

  1. Coughing
  2. Bluish tongue
  3. Lack of appetite
  4. Excess fatigue
  5. Very fast or slow heartbeat
  6. Difficulty in breathing

If you believe that your dog matches the criteria, go immediately to your vet.

Diagnosing heart murmurs in dogs

Your vet will carry out a number of tests to determine if your dog is affected by heart murmurs. Firstly, he will listen to the heart with a stethoscope to categorize the sounds. Then, he will proceed to grade the sound according to the scale previously mentioned. He should also carry out:

  • Blood test, more specifically a “complete blood count” to detect problems in major organs like the heart.
  • Chest X-rays to provide firsthand information about the heart and the lungs. This way, the heart can be visualised.
  • Electrocardiogram to aid in the detection of an abnormal heart rate.
  • Cardiac ultrasound of the heart to show the strength of the contraction and other relevant information which helps to determine if the valves are healthy.

Treatment of this disease

Treating heart murmurs in dogs depends on the severity of the murmurs. Vets can prescribe medication which can relieve the pressure that is affecting the heart. Likewise, your dog might need surgery to cure defects in heart wall and valves. Sometimes, a simple diet change can be enough to correct the cause of the murmurs.

Just remember that murmurs are a symptom of a more serious illness. Therefore, its treatment and recovery will vary depending on the underlying cause. Heart murmurs in dogs can be very harmful hence the importance of its early discovery.

More advice on...

What did you think of this advice article?

Thanks for your feedback !

Thanks for your feedback !

Leave a comment
Connect to comment
Want to share this article?